Determination of 4-hydroxyifosfamide concomitantly with ifosfamide and itsdechloroethylated metabolites using gas chromatography and a nitrogen phosphorus-selective detector

A sensitive gas chromatographic (GC)/nitrogen phosphorus detection (NPD) sy stem was developed for the determination of the antitumor drug ifosfamide ( Ifos) and its 2-dechloroethylifosfamide (2-Difos), 3-dechloroethylifosfamid e (3-Difos) and 4-hydroxyifosfamide (4-OHIfos) metabolites in human blood. 4-OHIfos was analyzed after coupling with a trapping agent and was used as an indicator of isophosphoramide mustard (IPM). Ifos and its metabolites 2- DIfos, 3-DIfos, 4-OHIfos and the internal standard (trofosfamide) were extr acted into chloroform and then resolved by gas chromatography using a Hewle tt Packard HP5 capillary column cross-linked with 5% phenyl methyl silicone (30 m; 530 mu m I.D.; 2.65 mu m film thickness). Precision and accuracy of the assay were determined over a three-day period and a concentration rang e of 3.25-50 mu g/ml for Ifos, 0.8-14 mu g/ml for 2D-Ifos, 0.6-10 mu g/ml f or 3D-Ifos and 0.08-1.40 mu g/ml for 4-OHIfos. The limit of quantitation wa s set at 3.25, 0.80, 0.62 and 0.08 mu g/ml, respectively, for Ifos, 2-DIfos , 3-DIfos and 4-OHIfos,The intra- and inter-day coefficients of variation a nd accuracies were less than 20%, except for a low concentration 4-OHIfos. This assay was then used to provide pharmacokinetic data on antitumor and t oxicologic effects following intravenous infusion of Ifos. (C) 1999 Publish ed by Elsevier Science B.V. All rights reserved.